Greeting v1.0 - http://www.bukkit.fr/?showtopic=6554

Greeting.java

package fr.neatmonster.greeting;

import net.minecraft.client.Minecraft;
import net.minecraft.client.gui.FontRenderer;
import net.minecraft.client.gui.ScaledResolution;
import net.minecraft.util.StringUtils;
import net.minecraftforge.client.event.ClientChatReceivedEvent;
import net.minecraftforge.client.event.RenderGameOverlayEvent;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.event.EventPriority;
import net.minecraftforge.event.ForgeSubscribe;

import org.lwjgl.opengl.GL11;

import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

import cpw.mods.fml.common.Mod;
import cpw.mods.fml.common.Mod.EventHandler;
import cpw.mods.fml.common.Mod.Instance;
import cpw.mods.fml.common.event.FMLPostInitializationEvent;

@Mod(modid = "greeting", name = "Greeting", version = "1.0")
public class Greeting {
    @Instance(value = "greeting")
	public static Greeting instance;

	private long ending = 0L;
	private String message = "";

	@EventHandler
	public void postInit(final FMLPostInitializationEvent event) {
		MinecraftForge.EVENT_BUS.register(this);
	}

	@ForgeSubscribe(priority = EventPriority.NORMAL)
	public void onRenderGameOverlay(final RenderGameOverlayEvent.Post event) {
		if (event.type == RenderGameOverlayEvent.ElementType.TEXT
				&& !message.isEmpty() && ending > System.currentTimeMillis()) {
			final FontRenderer fontRenderer = Minecraft.getMinecraft().fontRenderer;
			GL11.glEnable(GL11.GL_BLEND);
			GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);
			final int transparency = Math.round((ending - System.currentTimeMillis()) / 12f);
			fontRenderer.drawStringWithShadow(message, (event.resolution.getScaledWidth() - fontRenderer.getStringWidth(message)) / 2,
							Math.round(0.3f * event.resolution.getScaledHeight()), 16777215 + (Math.max(5, transparency) << 24));
			GL11.glDisable(GL11.GL_BLEND);
		}
	}

	@ForgeSubscribe(priority = EventPriority.NORMAL)
	public void onChatMessage(final ClientChatReceivedEvent event) {
		try {
			final String message = ((JsonObject) new JsonParser()
					.parse(event.message)).get("text").getAsString();
			if (StringUtils.stripControlCodes(message).startsWith("** ")) {
				ending = System.currentTimeMillis() + 3000L;
				this.message = message.substring(3);
				event.setCanceled(true);
			}
		} catch (final Exception e) {
		}
	}
}